ABSTRACT: Inefficient elimination of CO2 during laparascopy leads to hypercapnia even in the absence of abnormal EtCO2. When N2O is used in anaesthetic management large volume of N2O are released during the first 5-10 min. of recovery. This outpouring of large volumes of N2O dilutes alveolar CO2 and may decrease respiratory drive and ventilation. This study was designed to observe changes in CO2 elimination pattern with N2O.

METHODS : 60 consented patients of ASA grade 1 and 2 for elective laparoscopic surgeries were enrolled. They were divided into group 1 without N2O in anesthetic mixture and group 2 with N2O. Vital parameters and EtCO2 monitoring was done at the time of desufflation for 15 min. R-R, Tidal volume and Machine was kept constant.

RESULTS : In group 1 significant increase of EtCO2 was seen on 4th min returns to preinsufflation values at 8th min. In group 2 increase was seen at 8th min, returned to pre insufflations value at 14th min. significant increase of heart rate, systolic and diastolic BP was seen corresponding to the EtCO2 levels.

CONCLUSIONS : Avoidance of N2O in anaesthetic mixture results in faster CO2 elimination in laparoscopic surgery and prevents hycpercarbia and its related heamodynamic changes. Because hypercapnia can exist even in absence of abnormal EtCO2, PaCO2 values in post OP period can give clear picture of severity of hypercapnia with N2O.